[REPOST] plpgsql : looping over multidimensional array : getting NULL for subdimension

On Wed, Dec 1, 2010 at 10:51 AM, Samba <saasira@gmail.com> wrote:

Hi all,

I'm trying to loop over a multidimensional array and find if any of the
elements in a sub-dimensional array are matching some known criteria but
facing issue with NULL for the sub arrays.

I have a data structure that looks like:

   some_array VARCHAR[][] :=
'{{samba,sarath,sreenivas},{samba,mukhesh,pavan}}';

I'm trying to assign the individual sub arrays to other array elements like:

  other-array VARCHAR[];

  other_array=some_array[1];

and I'm expecting to get '{samba,sarath,sreenivas}' for index 1 and
{samba,mukhesh,pavan} for index 2;
however, I'm getting NULL.

Can some one explain the way I can assign subarrays to other array elements
plpgsql?

There is no truly effective way to do that. you can however slice the
array which is almost as good:
other_array=some_array[1:1];
note this will give {{samba,sarath,sreenivas}}, not {samba,sarath,sreenivas}

merlin

Thank you Merlin for your answer,

I tried that and is working as you said.
But when I do
other_array=some_array[1:2];
I'm getting the entire
'{{samba,sarath,sreenivas},{samba,mukhesh,pavan}}';

not just the second subarray, i.e. '{{samba,mukhesh,pavan}}'.

Is there any way I can get only the corresponding slice of the array?

otherwise I need to call this function multiple times from my java
client, once per each sub-array which I think will more expensive
that doing it in just one stored procedure call.

Regards,
Samba

On Thu, Dec 2, 2010 at 2:04 AM, Merlin Moncure <mmoncure@gmail.com> wrote:

On Thu, Dec 2, 2010 at 9:03 AM, Samba <saasira@gmail.com> wrote:

Thank you  Merlin for your answer,

       I tried that and is working as you said.
       But when I do
                   other_array=some_array[1:2];
       I'm getting the entire
'{{samba,sarath,sreenivas},{samba,mukhesh,pavan}}';

       not just the second subarray, i.e. '{{samba,mukhesh,pavan}}'.

       Is there any way I can get only the corresponding slice of the array?

sure...some_array[2:2], etc

merlin

On Thu, Dec 2, 2010 at 12:20 PM, Merlin Moncure <mmoncure@gmail.com> wrote:

On Thu, Dec 2, 2010 at 9:03 AM, Samba <saasira@gmail.com> wrote:

Thank you  Merlin for your answer,

       I tried that and is working as you said.
       But when I do
                   other_array=some_array[1:2];
       I'm getting the entire
'{{samba,sarath,sreenivas},{samba,mukhesh,pavan}}';

       not just the second subarray, i.e. '{{samba,mukhesh,pavan}}'.

       Is there any way I can get only the corresponding slice of the array?

sure...some_array[2:2], etc

by the way, see:
http://archives.postgresql.org/pgsql-general/2010-04/msg01041.php (and
responses) for a more in depth treatment of the issue.

merlin